Design and Fabrication of Power Generating Manual Treadmill

Abstract – In today’s world due to ever increasing health consciousness and fitness the idea of building manual treadmill arises with some extra modification in the existing treadmill and with this, effort loss during exercise is also used for purpose of generation of electricity including a controller display circuit for showing parameters like timer, speed, distance, pulse rate and calories. With the provision of AC motor to the manual treadmill by means of gear transmission mechanism, the power is harnessed from the legs of the person performing exercise to the belt which is then transferred to the roller then to the AC motor by means of gear-pinion arrangement and electrical power so obtained is stored in battery by converting the AC current to constant DC by accommodation of bridge rectifier circuit.

INTRODUCTION
A Treadmill is a device generally used for walking or running while staying in the same place. The concept of treadmill came into existence from olden days when animals or humans (labours) where used for running the tread-wheel
for grinding grains. This concept further developed into reverse mechanism wherein the power now is used to rotate the motor accommodated on the treadmill then to rotate the belt provided, which further provide moving platform for the person who want to exercise his body to maintain in proper
shape by the provision of some electrical supply directly from AC mains. But in this paper we will explain about a manual (leg-powered) treadmill which can only rotate when walker push the belt with his feet as while running or
walking on treadmill. But the addition is that there is an installation of AC motor to harness electrical power, whose moving parts are mechanically coupled or connected with the moving parts of the machine (rollers) which moves when belt of the treadmill is moving. When the rotor (moving part)
of the AC motor starts moving or rotating it will produces emf across its output terminals. This generated emf can be used for charging of Battery or other purposes.

DESCRIPTION OF TREADMILL COMPONENTS

Roller
Roller is used to rotate the belt and used to reduce friction while walking or running and reduce the effort of a person and to produce maximum power.

Bearing
Bearings are used to freely rotate rollers and to support the rollers to neglect friction. The bearings are pressed in rollers by means of punching press machine.

Belt
Belt is used in an assembly to build tension along the rollers to build friction among the extreme rollers and to provide moving mechanism for the treadmill and to actuate motion in the assembly for the rotation of the roller to transmit
power to the AC motor to acquire desired current.

Gear
A Gear-Pinion arrangement is used wherein the pinion is coupled to the motor by means of adapter bush with variable nut-bolt size adjuster and gear is welded on the front roller.
The power from gear is then transmitted from roller to pinion and from pinion to motor shaft.

AC Motor
An AC motor is a device which is used as dynamo in the circuit arrangement for conversion of mechanical energy into electrical energy it is in direct couple with pinion by means of adapter bush to the AC motor.

Bridge Rectifier
The simple working of the complete electrical circuit is when we run or walk on the treadmill the AC generator converts mechanical energy into electrical energy that generated AC current is transferred to the Bridge rectifier
where AC is converted to the Constant DC.

Battery
The provision of battery is made to store the current during the rotation of the motor which can then be used for further domestic purposes like illumination, rotating small motors, etc.

Control Panel Circuit & Spring Switch
Treadmill controller is designed for a wide variety of user preference, custom workouts with energy calculations based on individual weight, age, gender and target heart rate goal. The treadmill monitor display has the large bright display which shows Speed, Elapsed Time, Distance, Calories, Heart Rate and Target Heart Rate (user defined).

Working of Spring Switch
A Spring switch is same as that of reed switch but instead of ferrous strip enclosed in a glass casing, there is spring and small metal plate enclosed in a small plastic box casing, associating the wire to be taken out as output from both of these elements by soldering this wire on spring and metal plate and is used as an electromagnetic switch which helps control the flow of electricity in a circuit through panel. Whenever the permanent magnet fastened on pulley
come close to the spring switch while rotating, the magnetic field due to the magnet causes spring to come towards the plate and complete the circuit and vice-versa i.e. switch causes ON(1) and OFF(0) effect giving rise to some
commands embedded on circuit and showing the output on panel.

Working Principle
The same concept which is used in bicycle generator is used in treadmill generator for power generation in the form of electricity. In treadmill generator the AC motor is used for conversion of mechanical energy into electrical energy.
When the person operates the treadmill the power transmitted due to the effort so obtained is directly transferred to the rotor of AC motor which the actuates the emf due to which reverse current flows from motor to its output in form of electrical energy which is in the form of ac to make use of the energy so obtained is rectified to constant dc by means of bridge rectifier circuit to charge batteries and for lighting the led bulb or for other requirements.

Design and Fabrication of Power Generating Manual Treadmill

Motor Rating and Some Specification

In our project we have used a AC motor of rating:
Speed: 2200 rpm
Power Output: 18 watts
Current Output: 0.65 amps
Output from AC Motor when measured:
Current output: 0.3-0.6 amps
Voltage output: 17.5-26.67 volts
Power output: 7-16 watts